China's milk crisis has become a global problem, but what can be done about it?

What are the issues?

Can a nation prevent tainted food products from being imported in this age of free trade and global economies?

Yes.

Countries can prevent tainted food products from entering their borders, but they must do so in accordance with legal guidelines and with the backing of sound scientific data.

What is the controlling international law?

When a problem revolves around trade of a product across borders, you sound immediately look to the World Trade Organization (WTO) agreements. These are a system of treaties that have established trade guidelines that must be followed by the participating member states.

Both the U.S. and China are WTO members.

The U.S. is one of the original signors in 1995, while China acceded to the agreements in 2001.

This means that both the U.S. and China are bound by the WTO agreements, which limits what they can and cannot do in regards to international trade.

Annex A 1 (b) tells us that sanitary or phytosanitary measure are any measure taken:

"to protect human or animal life or health within the territory of the Member from risks arising from additives, contaminants, toxins or disease-causing organisms in foods, beverages or feedstuffs..."

It seems to me that preventing industrial chemicals being used as a food additive from poisoning infants and children is exactly in the province of this Agreement.

Annex C allows member states to check and ensure that products meet sanity & phytosanitary measures so long as they do not impose undue delay or unfavorable processes on imported goods.

So, WTO members have permission to check incoming food imports.

Article 5 of the agreement stops member states from banning food imports without justification. Member states must use risk assessment techiniques appropriate to the circumstances and based on international standards or sound scientific data.

In this case, it is well documented that melamine is harmful to humans. It is a chemical used in plastics production that leads to kidney stones and other health problems when consumed.